Needle stick injury is one of the most common occupational health hazards among healthcare professionals. Those involved in both the dental and medical professions are constantly at risk of dangerous patient-to-staff transmission of AIDS, hepatitis-B and other blood borne diseases from a contaminated needle.
In recent years, with the increase in dangerous communicable diseases, and particularly the growth of the fatal disease known as AIDS (acquired immune deficiency syndrome), it has become critical to eliminate the incidence of needlestick injuries to personnel in the medical profession, and elsewhere, due to contaminated needles of used syringes. There is a constant risk to the medical profession of contracting the disease of an infected patient by being scratched or pricked from the contaminated needle of a used syringe.
A number of designs of syringes which include features for protecting the exposed needle after use of the syringe have been developed and patented in recent years. The following patents are exemplary and not exhaustive.
U.S. Pat. No. 4,655,751, granted Apr. 7, 1987, Harbaugh, discloses a syringe which has a concentric protective shell over the barrel of the syringe. The shell is spaced outwardly from the barrel of the syringe and is slidable between a first needle-exposing position and a second needle-covering position. The shell has windows or a grid to permit viewing of the barrel of the syringe. A number of spacer ears on the barrel's outer surface permit the shell to be temporarily locked into mating pockets with the barrel.
U.S. Pat. No. 4,631,057, granted Dec. 23, 1986, Sampson, discloses an apparatus for injecting a substance into a human or animal. The apparatus includes a body, a needle coupled to the body, and a needle guard mounted on the body for movement from a retracted position in which the guard does not shield the needle to an extended position in which the guard shields the needle. The needle guard can be releasable retained in the retracted position and locked in the extended position. Locking of the needle guard is accomplished by interlocking members carried by the needle guard and by a collar mounted on the body.
U.S. Pat. No. 4,573,976, granted Mar. 4, 1986, Sampson, protects a syringe design which has a needle guard mounted on the body of the syringe, the guard being extendible so that it obstructs access to the point of the needle. The guard can be retracted over the barrel of the syringe to expose the point of the needle. Interlocking members on the body and the guard permit the guard to be releasably locked in the retracted or the extended position.
U.S. Pat. No. 4,425,120, granted Jan. 10, 1984, Sampson, discloses a hypodermic syringe comprising a barrel, a needle coupled to the barrel, and a needle guard mounted on the barrel for movement between an extended position in which the guard shields the needle, and a retracted position in which the guard does not shield the needle. The guard can be locked in either the extended or the retracted position. Locking of the guard is accomplished by a track on the internal surface of the guard and a track engaging member on the barrel.
U.S. Pat. No. 4,859,182, Nerli, discloses a dental syringe of the type having a beak for dispensing fluids into an oral cavity. The syringe comprises a sheath, the sheath being a form fitted, generally elongated tube or cylinder adapted to substantially fit over and cover the beak. The sheath is removably attached to the beak, and provides a substantially sterile outer-covering for the beak. The sheath has an open end and a terminal end having an aperture to allow a fluid to be dispensed from the beak and the sheath. The aperture is located near a discharge orifice of the beak through which the fluid is dispensed. The tip is located at the terminal end of the sheath, the tip and the sheath providing a substantially sterile outer-covering for the beak and the discharge orifice. The tip has a valve coincident with the discharge orifice. The valve allows the fluid to be dispensed from the beak and the tip. The valve substantially prevents contaminants from entering or being drawn into the beak through the discharge orifice.
U.S. Pat. No. 4,826,490, Byrne et al., discloses a safety device for a hypodermic needle. Byrne discloses a disposable non-reusable hypodermic needle assembly comprising: a needle support housing having a connector formation for removable attachment with the apparatus; a hypodermic needle supported by the housing for communication with the apparatus by way of the formation, one end portion of the needle projects from the housing remotely from the formation, and a sheath surrounding the housing and mounted thereon for movement in the longitudinal direction of the needle from a first position nearer to the formation and in which first position the needle one end portion is exposed, to a second position further from the formation and in which second position the needle end is enclosed within the sheath.
U.S. Pat. No. 4,907,968, Elsner, discloses a dental syringe shield or prophylactic which has a removable disposable dental syringe shield for placement over and in proximate contact with the nozzle of a dental syringe. The design includes an elongated cylindrical portion for fitting over the nozzle of the dental syringe and a barrel portion for fitting over the nozzle securing means of the dental syringe. The design also includes a backsplash collar shield, which fits over the nozzle portion and abuts the front of the base portion of the dental syringe.
U.S. Pat. No. 4,898,590, Andors, discloses a syringe comprising: a barrel including longitudinal walls defining an elongate chamber therein for receiving a cartridge; a first, elongate opening defined within the longitudinal walls through which a cartridge may be inserted into the chamber; a second opening defined within the longitudinal walls of the barrel, the second opening in opposing relation to the first elongate opening; and a sleeve slidably mounted to the barrel. The sleeve includes a first elongate opening and a second opening; the second sleeve opening being in opposing relation to the first elongate sleeve opening, the sleeve is movable to a position with respect to the barrel such that the first and second sleeve openings are substantially in register with the first and second barrel openings. The design includes means for retaining the sleeve upon the barrel.
U.S. Pat. No. 4,915,702, Haber et al. discloses a shielded safety syringe comprising an inner syringe cylinder having proximal and distal ends, a hypodermic needle supported at and extending outwardly from the distal end, and an outer protective sleeve having proximal and distal ends. The outer sleeve coaxially alignes with an axially advanceable relative to the inner cylinder from a retracted position, where the needle projects outwardly through an opening in the distal end of the sleeve, to an extended position, where the needle is located within and completely surrounded by the sleeve. A first groove is formed in the inner cylinder and locking means are pivotally interconnected with the outer sleeve and rotatable between unlocked and locked conditions, the locking means rotated to the locked condition for receipt within the groove formed in the inner cylinder when the outer sleeve is advanced axially from the retracted to the extended position relative to the inner cylinder.
Patent Cooperation Treaty, international publication no. WO 90/00073 dated 11 Jan. 1990, discloses a single-use injection needle, in particular for dental applications. The syringe comprises a handle including a piston and a support part for a sleeve having an interlocking structure through which the piston extends. The syringe also comprises a syringe body having a tubular end with an inter-locking structure cooperating with that of the sleeve of the handle. The shape is adapted to interlock with the sleeve, and a protecting shell having a locking section capable of covering the tubular end and the sleeve so that they are locked in their interlocking position. The protective shell is adapted for sliding along the syringe body between two extreme positions, i.e. a forward position where it totally covers the injection needle and a pulled-back position where it frees it and covers the interlocked tubular end and sleeve.